1. Field of the Invention
The present invention relates to trim edging applied in situ during drywall construction, and particularly to a trim strip used to achieve an attractive and uniform reveal between the top edges of upright drywall sheets and the underside of a ceiling.
2. Prior Art
The most common trim strip used in finishing drywall edges is of L cross section. For example, FIG. 1 and FIG. 2 of Dunlap U.S. Pat. No. 2,593,859, issued Apr. 22, 1952, show such a trim strip applied at an outside corner where mutually perpendicular drywall sheets abut.
L section trim strips also have been used when it is desired to have a narrow reveal between the top edges of drywall sheets and a ceiling. In that instance, the top plate or track of the supporting structure can be painted black to emphasize the reveal prior to installation of the drywall sheets. An L section trim strip is applied with one leg or flange extending over the top edges and the other leg or flange extending downward and overlying the top margin of the upright panel. Plasterlike finishing compound is applied over the downward-extending flange and feathered toward the panel to mask the trim strip, usually with an intermediate strip of joint tape.
FIG. 4 of Dunlap Pat. No. 2,593,859 discloses a modified trim strip of generally Z cross section having parallel offset flanges projecting oppositely from a central web. Dunlap proposed that such modified Z section trim strip be utilized when a set back of the drywall edge is desired adjacent to a door or window jamb. The same general type of Z section strip designated "shadow mold" is sold by Flannery, Inc. of Pacoima, California, to form a reveal along inside corners including horizontal inside corners formed between the top of a wall partition and a ceiling.
Groshong U.S. Pat. No. 4,598,516, issued July 8, 1986, discloses a modified L section trim strip designed for use with suspended ceilings; and Uttley et al. U.S. Pat. No. 4,587,781, issued May 13, 1986, and Rutherford U.S. Pat. No. 4,074,478, issued Feb. 21, 1978, disclose trim strips of generally T cross section that may be utilized with suspended ceilings.